Technical Abstract:
ARS researchers developed the tests to detect Shiga-toxin-producing E. coli (STEC) strains, such as E. coli O157:H7 in cattle feces and beef. These bacteria form toxins and other proteins that contribute to diarrhea in infected animals. The new test uses a technique called fluorescent PCR (polymerase chain reaction). In this process, scientists first amplify the organism's DNA using PCR. Then they use a fluorescent detector to illuminate the DNA. Results from the test can be obtained within 4 hours, which is 4 to 8 hours faster than other laboratory procedures. The researchers tested more than 60 strains, demonstrating 100 percent accuracy in detecting STEC and distinguishing E. coli O157:H7 from other STEC strains. These tests will be useful to cattle producers and veterinarians for fast diagnosis of diarrhea caused by STEC bacteria in calves. Cattle producers need this information to meet federal restrictions against the presence of E. coli O157:H7 on animal carcasses. The bacteria are transmitted to humans who eat foods contaminated with infected animal feces. About 20,000 human cases of E. coli O157:H7 infection are reported annually in the U.S., according to the Centers for Disease Control and Prevention.